1. Field of the Invention
This invention relates to electromagnetic flowmeters, and more particularly to a flowmeter having a cylindrical housing and having components integrated to mitigate many types of stress.
2. Description of the Related Art
Electromagnetic flowmeters are typically inserted between two flanges of a pipe to measure a volume of fluid flowing through the pipe. Examples of known electromagnetic flowmeters will be described with reference to FIGS. 1, 2 and 3.
One known flowmeter is shown in FIG. 1. This electromagnetic flowmeter generally comprises a conduit 1, which provides a path for a fluid, and a pair of coils 2a and 2b provided on the outer surface of conduit 1. The coils 2a and 2b are compressed by a core portion 5 to define a magnetic path. The core 5 is connected to the conduit 1 studs 3 and screws 4. Electrodes 6a and 6b protrude through oppositely disposed apertures in the conduit 1.
Another known flowmeter is shown in FIG. 2. In this example, the coils 2a and 2b are fixed in place by the cores 5a and 5b, which are connected at opposing end portions by screws 7a and 7b.
However, in the examples described above, as the cores 5a and 5b are compressed by the screws 4, or 7a and 7b, a compressive stress is generated which causes the shape of cores 5a and 5b and conduit 1 to partially deform. This deformation is a problem, because the resultant restriction of the flow path renders it difficult to measure the amount of fluid flow with the necessary degree of precision.
Another known electromagnetic flowmeter is shown in FIG. 3. This type of flowmeter is disclosed in U.S. Pat. No. 4,420,982. In this example, it can be seen that conduit 1 has end faces. When the flowmeter is installed between two pipe flanges 29 and 30, by bolts and nuts 8, a compressive force is applied in the axial direction of the flowmeter by pipes 9a and 9b, compressing both conduit 1 and a core portion 5. The conduit 1, in particular, must be designed with sufficient strength, or else be provided with some type of stiffening liner, in order to withstand this compressive force. This results in the flowmeter becoming more expensive to manufacture.
Further it is important that coils 2a and 2b be positioned against the conduit at the proper spacing relative to one another in order to measure the amount of flow of the fluid accurately. However, when assembling a flowmeter having the configuration shown in FIGS. 1 and 2, it is difficult to position coils 2a and 2b properly without specific tools and skilled labor. This results in a significant increase in manufacturing time and expense.